There is an area of endeavor devoted to the use of electomagnetic, and also photoelectric, transducers at relatively slow scanning velocities and at varying rates. The most common situation is found in hand scanning, as in supermarket applications, and manual pass-through, as in personnel access and tracing systems.
One well-known application of the apparatus according to the invention resides in the field of conventional magnetic stripe card records, the record of which is translated by a conventional magnetic transducer. The basic card presently utilized in Card Accessing (CA) systems is the American Banking Association standard, single track, magnetically encoded card. The data encoded in the magnetic stripe area of the card is recorded at a density of 29.5 bits per centimeter (75 bits per inch) in a F2F manner. In use, the magnetic recording surface passing electromagnetic transducer develops a signal. In applications such as CA systems, the terminal is a manually operated device in which the card is drawn across the transducer manually by the user. Due to this, the velocity of the magnetic surface as it passes the transducer varies greatly. This variation in card velocity results in a highly variable data rate at the output with the transducer.
In practical applications, the velocity of 4 to 12 inches per second are encountered in manual card read operations. These variations are encountered in a single read cycle and result in sizable change(s) in the data rate variable at the read head. This variable rate is difficult for a CPU to handle and results in a high read-retry or error rate and incompatibility with standard modems and like telecommunications devices.
Serious problems have been met in this area. Solutions have been suggested that in most cases are based on the phenomena present and data taken on the relatively higher speed recording and reproducing systems, although not all of the effort has neglected the lower speed aspects of the various arrangements. Most, if not all, of the prior arrangements have been both complex and expensive.